diff options
| author | Ross Zwisler <ross.zwisler@linux.intel.com> | 2017-10-12 11:52:34 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2017-10-12 11:52:34 -0400 |
| commit | 559db4c6d784ceedc2a5418ced4d357cb843e221 (patch) | |
| tree | be6a1f50c715af12510c45a7632a445efa4c1cd6 /fs/ext4/super.c | |
| parent | 51e3ae81ec58e95f10a98ef3dd6d7bce5d8e35a2 (diff) | |
| download | linux-559db4c6d784ceedc2a5418ced4d357cb843e221.tar.bz2 | |
ext4: prevent data corruption with inline data + DAX
If an inode has inline data it is currently prevented from using DAX by a
check in ext4_set_inode_flags(). When the inode grows inline data via
ext4_create_inline_data() or removes its inline data via
ext4_destroy_inline_data_nolock(), the value of S_DAX can change.
Currently these changes are unsafe because we don't hold off page faults
and I/O, write back dirty radix tree entries and invalidate all mappings.
There are also issues with mm-level races when changing the value of S_DAX,
as well as issues with the VM_MIXEDMAP flag:
https://www.spinics.net/lists/linux-xfs/msg09859.html
The unsafe transition of S_DAX can reliably cause data corruption, as shown
by the following fstest:
https://patchwork.kernel.org/patch/9948381/
Fix this issue by preventing the DAX mount option from being used on
filesystems that were created to support inline data. Inline data is an
option given to mkfs.ext4.
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
CC: stable@vger.kernel.org
Diffstat (limited to 'fs/ext4/super.c')
| -rw-r--r-- | fs/ext4/super.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/fs/ext4/super.c b/fs/ext4/super.c index b104096fce9e..986475c0d552 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3708,6 +3708,11 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) } if (sbi->s_mount_opt & EXT4_MOUNT_DAX) { + if (ext4_has_feature_inline_data(sb)) { + ext4_msg(sb, KERN_ERR, "Cannot use DAX on a filesystem" + " that may contain inline data"); + goto failed_mount; + } err = bdev_dax_supported(sb, blocksize); if (err) goto failed_mount; |